For the body to take in oxygen and give off carbon dioxide, two components of the respiratory system must function: (1) the lungs must function as a gas-exchanging organ; and (2) the respiratory pump that functions as a ventilation organ that transports air into the lungs and back out again. The breathing center in the brain, central and peripheral nerves, the osseous thorax, and the breathing musculature as well as free, stable respiratory paths are necessary for a correct functioning of the respiratory pump.
In certain diseases there is a constant overload on or exhaustion of the respiratory pump, which often results in respiratory insufficiency, with symptoms including dyspnea and exhaustion. A non-limiting example of a disease in which there is a constant overload on or exhaustion of the respiratory pump is chronic obstructive pulmonary disease (COPD) or pulmonary emphysema with a distended or flat-standing diaphragm. Flat-standing diaphragms have reduced ability to contract. Also, in patients suffering from pulmonary emphysema, respiratory paths are usually extremely slack and tend to collapse. Either a flat-standing diaphragm and/or slack respiratory paths may cause respiratory insufficiency. As a consequence of a flattened, over-extended diaphragm, the patient cannot inhale deeply enough. In addition, the patient cannot exhale sufficiently due to collapsing respiratory paths. This results in an insufficient respiration with an undersupply of oxygen and a rise of carbon dioxide in the blood, i.e., a respiratory insufficiency.
Patients with respiratory insufficiency often require or benefit from supplemental oxygen. However, the supplemental oxygen provided by conventional apparatuses and methods is frequently not adequate to increase ventilation and alleviate symptoms of dyspnea and exhaustion. For example, during periods of light exertion, the patient can become severely dyspneic and exhausted and suffer from elevated CO2 levels, due to the mechanical work associated with breathing which can be eight times more than the normal work required for healthy lungs.
A traditional mechanical ventilator can be used invasively with a tracheal tube or with a non-invasive nasal mask to assist in the work of breathing and alleviate dyspnea; however, conventional ventilators significantly limit upper airway functions, such as talking, eating, and swallowing, and also limit normal life activities such as ambulating and bathing. Hence, mechanical ventilators are rarely used voluntarily, and are predominantly used during acute treatment or for palliative care during late stage lung disease near the end of life.
Recently, new types of ventilation therapy have been described in U.S. Pat. Nos. 7,588,033 and 7,487,778. The new respiratory therapy methods and apparatuses described in these applications provide partial respiratory support in an open transtracheal ventilation system, so the patient can have normal upper airway function such as eating, smelling, drinking, talking, swallowing, and expectorating. Because of their unique delivery systems and ventilation output parameters, these new ventilators are able to be configured in a light weight tote-able or even wearable system to enable the patient to engage in other activities of daily life such as mobility, bathing, and exercise, which are not practical or possible when using conventional ventilators.
Because this new ventilation therapy enables activity and a more normal lifestyle, it now becomes meaningful to include in the ventilator's functionality certain intelligence and interactive features related to activity, health status, and lifestyle. These features would not be useful or even contemplated in a conventional ventilator.
Activity level and exercise tolerance is a key indicator of health status of a person with an illness. Maintaining or increasing the patient's activity level via ventilation therapy is described in U.S. Pat. Nos. 7,588,033 and 7,487,778. As maintaining a certain level of activity is expected to improve overall health status, is it is extremely meaningful to measure and track activity level, along with other related indices of health status, and to provide this information in a manner useful to the care provider and patient.
There is a need for improved patient feedback and monitoring in order to better assess the progress or regression in the health status of the patient and the degree of success of the ventilation therapy in enabling and promoting patient activity and overall health and quality of life.